my demonic chaos knight
by Wolfe the shadow
Summary: after Acnologia makes Mavis use fairy sphere. things nobody would guess about Natsu are told to a special requip knight. bad summary.


**Hay up with another fic hope you enjoy this.**

 **Paring for this will be Natsu x Erza, while I normally go with rare pairings I thought I would do this.**

 **Not going to say to much other then this starts right after Acnologia attacks. I don't own anything used other then my own ideas. Hope you enjoy.**

 **1 2 3 START**

"NATSU!" a female voice shouted amongst the darkness around her.

Erza scarlet looked around to find herself in a well of infinite blackness.

"My my. So you're here to. Don't worry you are not dead." a voice said.

The requip mage turned around to see a blond girl in a long dress. She had seen her before.

"Wait. you can't be. The first master?" Erza said looking at the small girl in shock.

"Hello Erza. glad to finally meet you, I am a big fan of your work. You really make my guild a unique place." the first master said to the knight.

"I cannot stay long. go see your friend." Mavis aid gesturing to the figure in the distance.

She then saw Natsu lying down and muttering in his looked back only to find Mavis gone.

She kneeled down next to Natsu, she knew she shouldn't but she leaned down and tried to hear what he was saying.

"Please no. these are my friends…...and the guild's sacred ground…..stop…..dad." Natsu slowly muttered.

Erza was shocked, was he having a crazy dream, was he dreaming about Igneel, or had Natsu lied to everyone. Was Igneel just made up so they didn't reject him in some way.

She did remember one time when they were kids Natsu was holding a black and blue flame in his hand and was crying, she just thought that he tried to copy Maco and starting into the fire reminded him of Igneel.

"Natsu?" Erza said as she shook him gently. He looks so peaceful like this, she had always been drawn to Natsu, he just seemed right in her eyes. Yes she used to love someone else and she was sad to say she could only see Simon as a brother, even if he felt much different about her.

"I'm sorry." Natsu softly said his eyes looking upwards at the blackness.

"Maybe if I used my real flames I could have stopped him." Natsu said.

"Do they have to do with what you were muttering in your sleep?" Erza asked him.

"Yea. guess I still sleep talk a lot, why do think I live so far away, so nobody would hear my constant nightmares and find out the truth. There's a lot people don't know. The truth is that dad switches between minds. He was originally human, but he used his own chaos flame dragon slayer magic too much and with a little punishment from Zeref. It turned him into that think we saw. That change drove him mad. He managed to hold on slightly, so he would switch between his normal surprisingly caring self and a rampaging beast. Every since I was a kid i've had nightmares about it. He never harmed me but to see that one person you care about most turn into. That thing. It's just too much. I still sometimes have night terrors." Natsu said sadly. The tales only tell of that thing not his father, it saddened him whenever he saw a page describing unending evil that was within the cursed dragon slayer.

"Now you have sorted that out I have some news, you are both stuck in part of the fairy sphere. Sadly due to the fact I had to guard against that much power I had to use to downside of the spell. For a massive increase in power it will place you in a time lock. Luckily I can alter this by choosing two people to remain aware, so for the seven months I can give you, you shall train here. I sense that part of your magic is surfacing Natsu, you better find your muramasa when you get out if you want to control it." Mavis quickly said before flickering away because utter lack of magic power.

They then appeared on the island but the whole place was covered in a golden barrier of light.

"Guess I better get used to using this again." Natsu said as he closed his eyes and concentrated. His imitation normal orange fire appeared before it started to lose colour. It then got darker and darker until it was pure black with highlights of blue flame. It then started to grow until it was about a 60:40 ratio to blue and black respectively. **(look up black and blue fire on google images and try thinking something like that)**

"You're gonna want to run. This much sealed magic, will cause quite a blast." Natsu said to Erza as she was shocked at the magic power and the amount of flames his body was giving off.

"RUN!" Natsu shouted as the fire started to rapidly grow in size.

Erza managed to run a safe distance away with the help of her flight armour. She stood amazed at the amount of magic power bursting out. It was almost choking.

"Hello Erza." a voice said behind the scarlet knight.

She saw a weird thought projection of Natsu there, he was covered in black markings and his smile had hints of a cruel smirk.

"So you're the one my wimpy other self is infatuated with hu. Well he could do a lot worse I guess." 'Natsu' said before laughing in a cruel way.

"Anyway I showed up to ask you to look after that idiot for me, also you two better get my muramasa back, also don't tell the other one, i'm just another part of him. You will know who I am soon enough." the alternate Natsu said before walking off.

 **2 months later**

"You're gonna have to try better then that!" Erza shouted as she easily dodged the salmon haired mage's strikes in her flight armour.

"You have seen nothing! **Hidden chaos art:wilted lotus:dark firestorm!** " Natsu shouted as he summoned a giant chaos fire tornado right where erza was standing. It was so fast she couldn't doge. She tried to stand up and fight but that magic rotting effect of the dark flames was taking a toll on her and her blades were both deformed because they had melted form a moment. So much it was more of a blunt weapon then a sword.

"This is not the old me. I was always so scared of my own power and people learning who I even am. You are not fighting Natsu the dragonslayer. But the real me. Dragonslayer prince:Natsu dragneel." Natsu said looking down at her. He really held back this much over all these years. But this Natsu. He was on another level. He was smart, less readable, and way faster, also the magic rotting effect was hard on her.

"Now come on I got a gift for you." Natsu said smiling at her and helping her up. He then released his rotting effect on her magic power.

What the magic rotting did was not eat away somone magic. It made it unusable, so if the fight went on for a long time they could not gain back as much power via ethernano could then use a secret art to instantly wipe out all the rotted magic and basically make them collapse from lack of magic power.

Went they got to the base camp that was made for the s-class trials they saw the rest of the group. They were just sleeping in the time lock. They were not harmed at all, that fact allowed the two to sleep at night.

Went they got back Natsu went into his tent and grabbed two things. The first thing he handed her was a strange looking katana.

"Here. take it, I feel you can control it." Natsu said giving her the blade.

"I found it in an underground vault, there's a bunch of other room with locks on them I will try and get into them." Natsu said.

The sheath had a name engraved on it. Yukianesa. **(from blazblue. I will maybe give erza some other blazblue weapons like a less op version of ouroboros)**

"Also take this, it should bolster your power." Natsu said as he handed her a blue and black piece of string.

"What is this?" Erza said. How would a piece of string help her.

"It's enchanted dragon scale cloth you dummie for your hair, like my scarf. It should boost your attack power.

"I know you don't normally have a ponytail so I should be able to fix up some more. We managed to knock a few scales of dad so I can make more just give me some time." Natsu said pointing to a pile of giant scales.

"Wait we damaged him, so he must not be that strong." Erza said thinking that dragons were not that big a deal. Which was kind of stupid on her part.

"HAHAHAHA. FUCKING THINK THAT WE HAHAHAHA! Hell no dragon scales can be used to form basically an anti magic barrier making it so nothing can damage them, dragon slayer magic can cut through that, there's no way dragon slaying magic on our level could cut through it. He didn't have that barrier up the entire fight, as Gildarts said, he was playing with us. I guess he let us break them off, he probably saw me, so he's still somewhat sane." Natsu said he was happy that he managed to break through his curse slightly and help him out, he could have used that roar way before Mavis could use fairy sphere, that was probably him too.

"Now we need to get working,Zeref made a get away and was probably planning something, Natsu insisted on getting ready for whatever the black mage was planning.

 **3 months later (2 months till the time lock closes in on them)**

After spending five months in each other's company Natsu and Erza had grown quite close. While Erza was happy with their relationship, part of her wished Natsu would make a move. She knew she could get quite forceful when she wanted something and she didn't want to freak him out.

Apparently the weapons he found were part of a vault hidden on the island. Mavis found them and locked them away because nobody was powerful enough to wield them. Her spirit warned them to not to use them, apparently she never payed much attention to Erza's way of doing things because she tamed all the weapons/objects useful to her arsenal.

"Oi, you gonna quit spacing out?" Natsu said, snapping Erza out of her daydream.

"You have gotten to not fear me much anymore Natsu, I'm going to correct this. **Hidden ice blade art: ARCTIC DUNGEON!** " the scarlet knight said as she stapped Yukianesa into the ground, a colossal amount of ice started to spread toward the dragon prince.

He barely had time to dodge as the ice formed spikes to get his leg. He then started running but the ice it appears was sentient and cased him down.

"Piss off. **Chaos fire dragon, roar!** " the slayer shouted as he unleashed a heavy amount of blue and black fire towards the living ice.

He managed to stop the attack only for the user of the technique to hold the responsible katana to his neck. He could feel the ice hold magic steel nibbling on his neck flesh.

"Ok fine. You're still scary, no doubt about it." Natsu said chuckling. " _Her neck, I could mark her right now, sorry Jellal, but she's mine."_ Natsu thought as he bit into Erza's neck, his instincts taking over his rational mind.

While this would normally hurt like hell, it felt strangely warm to Erza.

"Sorry!" Natsu said as he stepped back and mentally shot himself for what he just did.

"Natsu what did you do." Erza said as the puncture wound quickly closed and a strange mark appeared on her neck. It was the shape of a black dragon sitting on top of a book.

"I'M SO SORRY!" Natsu shouted.

"I marked you, it's ancient dragon magic. It bounds two people together for life, it probably stung like hell. I'm sorry." Natsu said looking down in shame. **(and yes I know this concept is overused af but I don't care)**

"Well no not really I felt kinda nice." Erza said looking down.

"Wait you like me back!" Natsu shouted at her.

"You like me in the first place!" Erza said back.

"Nice, it finally starts." Mavis said from the sidelines somehow having popcorn.

 **Hope you liked it guys. Leave some nice feedback in the comments.**


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